Google has really warmed up to Adobe, and together with an ever growing growing pushback caused by Flash' sorry performance and lack of security, this is pushing Adobe to really step up their game and finally bring Flash into the 21st century. Flash 10.1 on Windows is already a huge step forward, and on Mac OS X, too, Adobe is making progress. Linux still lags behind a bit, mostly due to the lack of hardware acceleration.
On the mobile side of things, Flash has always been pretty much unusable. You had light versions of the Flash player, but I doubt anyone really used those to any serious degree. With the mobile web becoming ever more prevalent, Adobe really had to get working, and it seems like this work is finally paying off.
There is some stutter here and there, but for a beta release, this isn't bad - especially when you consider where these guys are coming from. I do worry about the battery life issue, though; good performance is all well and minxy, but from this video we can't make out anything about how Flash 10.1 impacts battery life (the Nexus One is plugged in).
The release of Flash 10.1 for Android is tied to the release of Android 2.2 "Froyo", which Google is expected to unveil at this year's Gogle I/O conference later this month.